The present invention relates to a method of applying a treating agent such as a coloring solution to polymer products and a composition used for same. Particularly, it is concerned with a dyeing process for obtaining bleeding-prevented sharp and clear print patterns on sheet-like substrates such as fabrics by the ink jet or spray method, as well as an ink composition used for same.
Screen printing, roller printing, rotary printing and transfer printing methods have heretofore been adopted generally as textile printing methods. However, all of these conventional textile printing methods require a plate-making process and much labor and preparation period before goods production. Besides, notwithstanding the today's situation of diversified fashions and desire for multi-variety, small lot production, the above concentional textile printing methods are markedly lacking in instant printing capability. To remedy this inconvenience, developments are now under way in the field of recording or printing on paper. Above all, an ink jet recording process capable of printing without using plates is beginning to attract attention. When this process, mainly using paper, is applied to textiles, there occurs the problem of bleeding as a major problem. Textiles are not so water-absorbable as paper and have directionality and voids, so ink bleeding occurs to a large extent, making it difficult to obtain clear patterns.
To prevent such bleeding in fabrics, British Pat. No. 1,587,930 proposes a method in which natural carbohydrates (e.g. flour or starch derivative, alginate) are mixed in ink components, and fabric is pretreated with a coagulating agent (e.g. aluminum sulfate, sodium borate, borax).
Further, in U.S. Pat. No. 4,330,293 there is proposed a method in which a synthetic polymer containing carboxylic acid is mixed into ink and fabric is pretreated with an alkali compound.
However, according to the present inventors' study, the above methods involve the following drawbacks
(1) For thin fabrics, aside from thick fabrics such as carpets, bleeding cannot be prevented to a satisfactory extent.
(2) Although it is preferable that the ink viscosity be low in a high speed ink jet, it is impossible to obtain a satisfactory effect because only small amounts of natural carbohydrate and polycarboxylic acid can be incorporated in ink components from the standpoint of injection characteristic.
(3) The above known compounds cannot be used. because they exhibit a coagulating action against a water dispersion type ink such as a disperse dyestuff. Also against water-soluble dyestuffs, those compounds are apt to form gels.
(4) The pretreatment with an alkali compound causes a change in quality or decrease of tenacity of natural fibers such as wool and silk as well as synthetic fibers such as acrylic fibers.
Further, in Japanese Patent Laid Open No. 106989/1984 there is proposed a method in which a recording medium is pretreated with a metallic salt and a cationic substance and then an ink which comprises a water-soluble dyestuff is applied thereto to improve the resistance to water and to light. However, this proposed ink jet method is applied to paper, and if it is applied to fabric, a hydrophilic group (--SO.sub.3 Na) of the water-soluble dyestuff will be substituted by a metal, e.g. Ca, into [(--SO.sub.3).sub.2 Ca], resulting in deterioration of the water solubility, decrease of functional groups substantially bonded to the fabric and a marked reduction of dyeing affinity.